Implement passthrough for benchmark (#2580)

* Implement passthrough for benchmark

Add a new option -p,--passthrough to benchmark.
With this option, the benchmark command prints its results to stdout and passes the block's output to the next command in the pipeline.

* Add execution block for benchmark -p

`benchmark --passthrough` now takes a block where the benchmark output is sent.
Example:
`benchmark -p {save bench.toml} {ls}`

crates/nu-cli/src/commands/benchmark.rs

@@ -4,7 +4,10 @@ use crate::prelude::*;
 #[cfg(feature = "rich-benchmark")]
 use heim::cpu::time;
 use nu_errors::ShellError;
-use nu_protocol::{hir::Block, Dictionary, Signature, SyntaxShape, UntaggedValue, Value};
+use nu_protocol::{
+    hir::{Block, ClassifiedCommand, Commands, InternalCommand},
+    Dictionary, Scope, Signature, SyntaxShape, UntaggedValue, Value,
+};
 use std::convert::TryInto;
 use std::time::{Duration, Instant};
 
@@ -13,6 +16,7 @@ pub struct Benchmark;
 #[derive(Deserialize, Debug)]
 struct BenchmarkArgs {
     block: Block,
+    passthrough: Option<Block>,
 }
 
 #[async_trait]
@@ -22,11 +26,18 @@ impl WholeStreamCommand for Benchmark {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("benchmark").required(
-            "block",
-            SyntaxShape::Block,
-            "the block to run and benchmark",
-        )
+        Signature::build("benchmark")
+            .required(
+                "block",
+                SyntaxShape::Block,
+                "the block to run and benchmark",
+            )
+            .named(
+                "passthrough",
+                SyntaxShape::Block,
+                "Display the benchmark results and pass through the block's output",
+                Some('p'),
+            )
     }
 
     fn usage(&self) -> &str {
@@ -42,15 +53,21 @@ impl WholeStreamCommand for Benchmark {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Benchmarks a command within a block",
-            example: "benchmark { sleep 500ms }",
-            result: None,
-        }]
+        vec![
+            Example {
+                description: "Benchmarks a command within a block",
+                example: "benchmark { sleep 500ms }",
+                result: None,
+            },
+            Example {
+                description: "Benchmarks a command within a block and passes its output through",
+                example: "echo 45 | benchmark { sleep 500ms } --passthrough {}",
+                result: Some(vec![UntaggedValue::int(45).into()]),
+            },
+        ]
     }
 }
 
-#[cfg(feature = "rich-benchmark")]
 async fn benchmark(
     raw_args: CommandArgs,
     registry: &CommandRegistry,
@@ -60,10 +77,11 @@ async fn benchmark(
     let tag = raw_args.call_info.args.span;
     let mut context = EvaluationContext::from_raw(&raw_args, &registry);
     let scope = raw_args.call_info.scope.clone();
-    let (BenchmarkArgs { block }, input) = raw_args.process(&registry).await?;
+    let (BenchmarkArgs { block, passthrough }, input) = raw_args.process(&registry).await?;
 
     let start_time = Instant::now();
 
+    #[cfg(feature = "rich-benchmark")]
     let start = time().await;
 
     let result = run_block(
@@ -75,30 +93,41 @@ async fn benchmark(
         &scope.env,
     )
     .await;
-    let _ = result?.drain_vec().await;
+    let output = result?.into_vec().await;
 
+    #[cfg(feature = "rich-benchmark")]
     let end = time().await;
 
     let end_time = Instant::now();
     context.clear_errors();
 
+    // return basic runtime
+    #[cfg(not(feature = "rich-benchmark"))]
+    {
+        let mut indexmap = IndexMap::with_capacity(1);
+
+        let real_time = into_big_int(end_time - start_time);
+        indexmap.insert("real time".to_string(), real_time);
+        benchmark_output(indexmap, output, passthrough, &tag, &mut context, &scope).await
+    }
+    // return advanced stats
+    #[cfg(feature = "rich-benchmark")]
     if let (Ok(start), Ok(end)) = (start, end) {
         let mut indexmap = IndexMap::with_capacity(4);
 
-        let real_time = into_value(end_time - start_time, &tag);
+        let real_time = into_big_int(end_time - start_time);
         indexmap.insert("real time".to_string(), real_time);
 
-        let user_time = into_value(end.user() - start.user(), &tag);
+        let user_time = into_big_int(end.user() - start.user());
         indexmap.insert("user time".to_string(), user_time);
 
-        let system_time = into_value(end.system() - start.system(), &tag);
+        let system_time = into_big_int(end.system() - start.system());
         indexmap.insert("system time".to_string(), system_time);
 
-        let idle_time = into_value(end.idle() - start.idle(), &tag);
+        let idle_time = into_big_int(end.idle() - start.idle());
         indexmap.insert("idle time".to_string(), idle_time);
 
-        let value = UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag);
-        Ok(OutputStream::one(value))
+        benchmark_output(indexmap, output, passthrough, &tag, &mut context, &scope).await
     } else {
         Err(ShellError::untagged_runtime_error(
             "Could not retreive CPU time",
@@ -106,49 +135,68 @@ async fn benchmark(
     }
 }
 
-#[cfg(not(feature = "rich-benchmark"))]
-async fn benchmark(
-    raw_args: CommandArgs,
-    registry: &CommandRegistry,
-) -> Result<OutputStream, ShellError> {
-    let registry = registry.clone();
+async fn benchmark_output<T, Output>(
+    indexmap: IndexMap<String, BigInt>,
+    block_output: Output,
+    passthrough: Option<Block>,
+    tag: T,
+    context: &mut EvaluationContext,
+    scope: &Scope,
+) -> Result<OutputStream, ShellError>
+where
+    T: Into<Tag> + Copy,
+    Output: Into<OutputStream>,
+{
+    let value = UntaggedValue::Row(Dictionary::from(
+        indexmap
+            .into_iter()
+            .map(|(k, v)| (k, UntaggedValue::duration(v).into_value(tag)))
+            .collect::<IndexMap<String, Value>>(),
+    ))
+    .into_value(tag);
 
-    let tag = raw_args.call_info.args.span;
-    let mut context = EvaluationContext::from_raw(&raw_args, &registry);
-    let scope = raw_args.call_info.scope.clone();
-    let (BenchmarkArgs { block }, input) = raw_args.process(&registry).await?;
+    if let Some(time_block) = passthrough {
+        let benchmark_output = InputStream::one(value);
 
-    let start_time = Instant::now();
+        // add autoview for an empty block
+        let time_block = add_implicit_autoview(time_block);
 
-    let result = run_block(
-        &block,
-        &mut context,
-        input,
-        &scope.it,
-        &scope.vars,
-        &scope.env,
-    )
-    .await;
-    let _ = result?.drain_vec().await;
+        let _ = run_block(
+            &time_block,
+            context,
+            benchmark_output,
+            &scope.it,
+            &scope.vars,
+            &scope.env,
+        )
+        .await?;
+        context.clear_errors();
 
-    let end_time = Instant::now();
-    context.clear_errors();
-
-    let mut indexmap = IndexMap::with_capacity(4);
-
-    let real_time = into_value(end_time - start_time, &tag);
-    indexmap.insert("real time".to_string(), real_time);
-
-    let value = UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag);
-    Ok(OutputStream::one(value))
+        Ok(block_output.into())
+    } else {
+        let benchmark_output = OutputStream::one(value);
+        Ok(benchmark_output)
+    }
 }
 
-fn into_value<T: TryInto<Duration>>(time: T, tag: &Span) -> Value {
-    UntaggedValue::duration(
-        time.try_into()
-            .unwrap_or_else(|_| Duration::new(0, 0))
-            .as_nanos()
-            .into(),
-    )
-    .into_value(tag)
+fn add_implicit_autoview(mut block: Block) -> Block {
+    if block.block.is_empty() {
+        block.push({
+            let mut commands = Commands::new(block.span);
+            commands.push(ClassifiedCommand::Internal(InternalCommand::new(
+                "autoview".to_string(),
+                block.span,
+                block.span,
+            )));
+            commands
+        });
+    }
+    block
+}
+
+fn into_big_int<T: TryInto<Duration>>(time: T) -> BigInt {
+    time.try_into()
+        .unwrap_or_else(|_| Duration::new(0, 0))
+        .as_nanos()
+        .into()
 }